Esophageal switch for electrocardiograph apparatus



M. H. PELAVIN Aug. 4, 1953 ESOPHAGEAL SWITCH FOR ELECTROCARDIOGRAPH APPARATUS Filed May 6, 1950 @www0 FHQUE/VCY- cya/es per sconol R. www mw u NA m w ma L L m M mw WW m T M C .d 2 JT y. Jv 2 .B 8 w M y ,i w TI M E w gli.; M 2 )1 E A A. A M uw w Emil. www A m E .M2 m Og MMC M D/ Il f 53:0 mi M M T WMM* HTTORNE YS Patented ug. 4, 1953 ESOPHAGEAL SWITCH FOR ELECTRO- CARDIOGRAPH APPARATUS Milton H. Pelavin,"Brooklyn, N. Y., assignor to Technicon Cardiograph Corporation, New York, N. Y., a corporation of New York Application May 6, 1950, Serial No.'160,511

The present invention relates to multiple-lead electrocardiographs and to electrical and electronic circuits therefor.

In application Ser. No. 762,633, filed July 22, 1947, and assigned to the assignee hereof, there is disclosed and claimed a` multiple-lead electrocardiograph operable to produce simultaneously and directly on a record web or sheet a plurality of graphs or traces of body voltage variations transmitted from the subject by the several leads, respectively, and to produce said graphs or traces on the web or record sheet in such manner that they all have an identical time relation with respect to each other. In the apparatus described in said application, provision is made for recording of the standard (interextremity) potentials, designated in cardiology as leads I, II, and III, for recording unipolar chest voltages, designated in cardiology as the chest or precordial leads, and for recording the augmented unipolar extremity leads, designated in cardiology as the aVR, aVL and aVF leads. A lead selector switch is provided in said apparatus for connecting the different sets of leads to the companion channels, respectively, each of which includes electronic amplifying means for amplifying the body voltages transmitted to said channels in accordance with the setting of the selector switch. The unipolar precordial or chest leads record the potentials from the anterior surface of the heart. In order to obtain unipolar leads, whether from the chest or from the extremities, a special connection, known in cardiology as an indifferent electrode of zero potential, for example, the Wilson terminal, or the Goldberger terminal, is used in conjunction with a precordial electrode or with a unipolar extremity electrode, as the case may be, said latter electrodes being designated as the exploring electrode. In A primer of electrocardiography by Burch and Winsor, published by Lea & Febiger, 1949, it is pointed out, on page 132, that frequently-because of the posi- 10 Claims. (Cl. 12S-2.06)

ltion of the heart or, as a result of the disease thereof, it is necessary to employ positions on the body for the exploring precordial electrode which are more to the right or left or above or below the usual six sites of the multiple precordial leads. If it is desired to determine the electric activity of the heart auricles or of the posterior wall of the heart ventricle, the exploring electrode is placed in the esophagus at the level at which `the left auricle or ventricle rests against this organ, the indifferent electrode being placed, as described therein. When so used to obtain indications of the electric activity of the heart, these electrodes constitute the esophageal lead. As indicated on page 132 of said volume, the esophageal lead is used when it is impossible to identify P waves in the standard leads and it is especially desirablein the study of auricular depolarization. The P waves in the esophageal leads are usually peaked and of great amplitude. The esophageal leadis also used to identify and study posterior myocardial infarction. However,` it has been found that the esophageal leads, in addition to transmitting desired voltages repre-- sentative of the condition of the heart, also trans-v Init undesired incidental body voltages, such as, for example, vthe very low frequency breathingor respiratory voltages, in addition to gastric voltages, all of which are amplified and recorded in the electrocardiograph. Said incidental voltages are often relatvelylarge and tend to cbscure the desired electrocardiograph recordings representative of the condition of the heart, known in cardiology as the ECG make it dificult to obtain consistent readings thereof.

In accordance with the present invention and pursuant tothe primary object thereof, provision is made for substantially attenuating or sup-V pressing incidental low frequency body voltages transmitted by the esophageal lead before they enter the amplifying channels of the electrocardiograph, while permitting the higher 'frequency voltages representative of the condition of the heart to enter the amplifying channels,I

with no appreciable attenuation.

A further object is the provision of a selector switch for recording three simultaneous esophageal leads or any desired combination of 'an esophageal` lead, a chest or precordial lead, and an intra-cardiac lead.

The above and other objects, features and advantages of the present invention will be more' fully understood from the following description. with the accompanying considered in connection illustrative drawings.

In the drawings:

Fig. 1 is a schematic illustration of a multiplelead electroeardiograph embodying the present invention; and

Fig. 2 is a curve illustrating the lowfrequency response characteristic of the apparatus ofthe present invention.

Referring now to the drawings, as shown 'in' Fig. 1, themultiple-lead electrocardiograph apparatus I0 is provided with three separate channels A, B and C, respectively. Each of said channels includes electronic amplifying means for amplifying the body voltages transmitted to said channels by leads from different parts of the subJects body. The electrical circuits of these channels are all alike, and may be of the type illustrated and described in the above identified applicatlon. If desired, each channel may be provided with a step-controlled sensitivity de complexes, and

sensitivity of all the channels may be altered, not only siinliltaneoilsly .lont substantially instante..-

neously -f-rpgrni'one sensitivity to another, With-- In laddition to the selector switch, illustrated# and described in the iirst above mentioned Aap.- plication, for recording the standard leads` I, II and lll, the nnipolar oreooroiai leads, andthe. alieinentell onlnolar extremity leads, .the eleono.-V oefiosraP/.h lll.' pursuant to the present invention? .isllovioled Wit/li the combination of eso.-

pna'aeai switon i4 .and -lead .selector svvitoli. It ror roordins three .simultaneous esophageal leads. or any Leonnioination of an esophageal ,leads che'stFor preootdlalieaa. and .anintra-.oaroiao lea-d!- SfWlt'oln i4. oolnnrises an esonh-aceal.eleo-` t'rode selector navinatnree separate sections 14n,

143i* ,and 14@ i es visere shown.. eaen of'saisi seo: tions is rrovidedwith fifteen' .fined .esophageal terminal oontaots designated as ECI through Eel 5; respectively. The linen oontasts ,of eaonof said sections areoonneoted in parallel .tonfteen esophageal leads designated .through E15. respectively.` Said esophageal leads are contained Vin the esophageal `tube I8 Which isin.- sorted into the esophagus of the .subject .in a man-nerful-ly described b y W. I-l; Brownin A study of the'oesophageal lead in clinical electro- Calfdoaophy" Published inthe Y.n.ienloan vTrleart Joornalrvollaoase l., 19.3.6- v.Ito/1.11 be understood that each-esophageal lead terminates in 4an esophageal electrode, not illustrated, which is positioned in the esophagus predetermined po-A sition relative to the subjects heart, forindicatinglfat each of said positions, voltages representative of the condition of the hearts .The HlQY-able contactsv of said switch sections IIIA, I4B and |40i are indicated at 20A, 20B and l520C, respec-A tivelyv` Saiol movable oontaots are oonneateo by lines 22A,'22B5and 22C; respectively, to the stationary contacts E of sections 16A, ISBand 15C., respectivelyoflead selector switch I6.` In order to attenuateor Isuppress comparatively large and ven-ydowirequency incidental body voltages, such as, for example,-breathing and gastric voltages, which are picked up by the esophageal electrode and transmitted by the esophageal lead, for pre.-

venting'.them-from.reaching the contacts lil-for l polar chest. voltages. In thisconnection it'will be..1 1nderstood` thaty the` precordial terminals a P l,

P1: and Flare. adapted to-be connected through suitable .lineslfto -precordialelectrodes positionahleon. thefsuloectis fbody. Said precordial terminals;are connected by the lines 30A, 30B and 30E, respectively-,to the stationary contacts P of Y intra-cardiac voltages. In this connection, it will loe understood .that the...intra.oar.diao .terminals lol, vIc2, and Ict. areadapted for tconnection throughl suitable lines to catheters provided with heart electrodes which are inserted through a vein of the subjects body for positioning said hea-rit .electrodes lin predetermined heart portions. |This.tool-inique is a known practice in cardiology and isldescribed bOtI-lby A. Battro and H. Bidoggia infllldoardiac-electrogram obtained by heart catheterigation rnfan, published in the American Heart Journal, vol. 33, page 604, 1947, and by H-.-'D:Levine,-H. K. Hellems, M. H. Wittenborgjanlzll. Dexter in Studies in intracardiac electrography in man, published in the American Journal, vol.. 37, page 64., 194.9. .Said terminals are .connected by., lines 32A, 372B and 32C, respectively, to the stationary contacts' I C i of selector swltohseotions .IGA...I6B and 16C, .re-

spent.ively..` Eaoh of said switch sections is also4 provided with .an ofi position at the stationary.

contact. @which is grounded 'through' the resistor .34.. preferably 10.00 ohms.

The .seleotor syvitoh sections are Provided with .the movable oontaots 36A, 36B and 36C. respectively, Wllionare-oonneoted toinlout terminals @oAMiiiB and 40C. respectively. of `Channels A, B and .Cyresoootivelyl The ooms-anion channel. input terminals 35e. 38B `and 38C. respeotively.

are eaon oonneoted to the central terminal CToii the indliierent yeleotrode of .Zero potential .which may be the ,Wilsons or Goldberger terminalh bothA fully desoriloed atnages 5.0 and 5l. of: lnioolar lead electrography by Goldberger, published'. by Lea 8; liebigerflQeQ; As here shown, saidelectrode oornPfises a Wilson terminal and is constituted by the terminals I .zflJ'RA and LLeach of which is `connected to terminal .CTthrough a resistor d2 which is preferably; 5000' ohms. It'will be understood that the terminals LARA and LL are adapted to be connectedv to the patient elec-v trodes designated in cardiology` as the; LA,` RA

and LL electrodeswhich are secured to'thej exs trernities.

In operating theV apparatus lila-'if itisdesircd',

that esophagealr 'voltage Vbe recorded `onA recorder V-I2 'at the output of channel for..

example,v movable'contact'A ismoved toposition Eef-selector switch section `l 5A andmovable contact'vllQA ot esophagealswitch section 14A ismovedto the desiredone ofthe iifteen *positions* thereof.l Inthe same-manner, voltages-trans mittedby the` vesophageal -leadmay be recordedr` at either or both ofi-theI outputs of channelsB" andy C,- i respectively;I by` properly positioning movable-contacts 36B -andSBC whereby to effectisaid-voltages.

undesirable.l for.l recording. body...voltages,vsuch las,` for example, breathing and gastric voltages,I tendto` obscure the recordA ing-ofthe desired voltages representative-'ofthe subjects heart condition andmake it'diiic'ultto obtain` consistent readings ofsaid` desired; volt-l T'he undesiredincidental lower frequency body voltages which ybev transmitted freinv the esophageal electrodesthrough the esophageal. switch are attenuated*beforegreaching the i ages terminals ofgthe respectivechannelsjdue 'Qjthe action of lter units 2.4 and therefore do not obscure the recording of voltages representative of the heart condition. In apparatus constructed and operated pursuant to the present invention,

the filter units were each constituted by a .5 microfarad capacitor-and a 220,000 ohm resistor. It was found that the time constant of 110,000 microseconds of such resistance-capacitance lterswas such as to provide a low frequency response for the electrocardiograph I0, as is illustrated by the curve 44 of Fig. 2. It will be noted, as indicated by that portion of said curve between points 46 and 48, that voltages having frequencies of four cycles per second, or higher, were passed with substantially no attenuation by filters 24. voltages of these frequencies, starting substantially at four cycles per second, represent the-body voltages desired to be recorded since they represent to the cardiologist the condition of the heart. Voltages having frequencies of less than four cycles per second, representing the incidental body voltages which are undesired for recording, are substantially suppressed or attenuated, as indicated by that portion of said curve between points 46 and 50, so that they do not obscure the recording of the representative heart voltages. The attenuation of said lower frequency voltages serves to stabilize the recording of the representative body voltages to produce consistent readings of said representative voltages.

By `positioning the movable contacts of selector switch sections IBA, IBB and IEC. voltages transmitted by various combinations of leads can be recorded simultaneously. voltages transmitted by an esophageal lead are being recorded through one channel, precordial voltages can be recorded through the second channel, and intracardiac voltages can be recorded through the third channel. As illustrated in Fig. 1, movable contact 36A is engaged with stationary contact Ic of switch section IBA to transmit an intra-cardiac voltage through channel A to the recorder, movable contact 36B is engaged with stationary contact P of switch section [6B to transmit a precordial voltage through `channel B to the recorder, and channel C is transmitting to the recorder a voltage from the esophageal lead E9 through stationary contact EC@ and movable contact 20C of switch sec-A tion [4C and from the latter through stationary contact E and movable contact 36C of switch section ISC. It will also be evident that various other combinations of transmitted voltages can be recorded, as desired. It will be apparent that, if desired, voltages may be recorded through only one or two of the channels, by positioning one or two of the movable contacts of selector switch I6 in the off positions thereof at contact O.

As illustrated, the present invention is embodied in a multiple-lead electrocardiograph but it will be readily understood that it is within the scope of my invention to apply the underlying idea to a uni-lead electrocardiograph for preventing the transmission of breathing and gastric voltages to` the electrocardiograph. Also the invention is not limited to a direct-writing electrocardiograph.

While I have shown and described the preferred embodiment of my invention, it will be understood that various changes may be made in the `Ipresent inventionwthout departing from the underlying idea or principles of the invention within the scope of the appended claims.

For example, while y Having thus described invention, what I claim and desire to secure by Letters Patent, is:v

r1. In an electrocardiograph, a channel for amplifying voltages transmitted thereto from the subjects body, electrical terminal means in cir-v cuit with the input to said channel for connection to an esophageal lead positionable in the subjects esophagus for investigating a condition of the subjects heart as indicated by voltages repre-A sentative of such condition, and filter means interposed in the circuit between said electrical terminal means and the input to said channel for substantially attenuating incidental body voltages of lower frequency than said representative voltages to prevent the transmission of said incidental lower frequency body voltages through the esophageal lead to said channel.

'2. In an electrocardiograph, a channel for amplifying voltages transmitted thereto from the subjects body, a terminal connector in circuit with the input to said channel for connection to an esophageal lead positionable in the subjects esophagus for investigating a condition of the subjects heart as indicated by voltages representative of such condition, and filter means interposed in the circuit between said terminalA connector and the input to said channel for substantially suppressing incidental body voltages of lower frequency than said representative voltages to prevent the transmission of said incidental.

lower frequency body voltages through thel esophageal lead to said channel, said filter means havinga time constant which permits the transmission therethrough of said representative voltages substantially without attenuation thereof.

3. In an electrocardiograph, a channel for amplifying voltages transmitted thereto from the subjects body, terminal connector means in circuit with the input to said channel for connection to an esophageal lead positionable in the subjects esophagus for investigating a condition of the subjects heart as indicated by voltages representative of such condition, and filter means interposed in the circuit between said first men-- tioned means and the input to said channel for substantially attenuating incidental body voltages of lower frequency than said representative voltages to prevent the transmission of said incidental lower frequency body voltages through the esophageal lead lto said channel, said filter means comprising a resistance-capacitance net work havinga time constant effective to substantially attenuate said incidental lower frequency body voltages and to pass said representative voltages therethrough substantiallyv without attenuation.

4. In an electrocardiograph, a channel for amplifying voltages transmitted thereto from the: subjects body, a terminal contact in circuit with the input to said channel for connection to an. esophageal lead positionable in the subjects; esophagus for investigating a condition of the: subjects heart as indicated by voltages repre-- sentative of such condition, and filter means; interposed in the circuit between said terminal. contact and the input to said channel for sub-- stantially attenuating incidental body voltages of' lower frequency than said representative voltages to prevent the transmission of said incidental lower frequency body voltages through the: esophageal lead to said channel, said filter means having a time constant which substan tial-ly attenuates voltages having frequencies lessv than substantially four cycles per second.

5. In an electrocardiograph, a channel for ted "thereto rein vthe htaotineiroaitwith ohheotohto .an esophageal leas vills-loonane. the suadente esoehae'hs.- tor investigating .eohaitioa ei..-u1e sobieote `heart asinoioated. lovvoltaeeazrenfe.- Sehtatl. e .i .eheh ...oonditohfand filter. means mtethose .in .the .ir-Cult between said terminal contest. .and the toeaid Channel .for sube stahtially attenuating-.incidental-loods voltages .of lower? freooehey-.than sato .representative voltages to prevent the trahsmisaiohof ...saidincidental lower .frequency boos. voltages: through. the esophageal lottato Said. oha-hheh said filter means havhoe` a .time constant of f substantially 1100051 .microseconds vhoh. is.y eieetive. to. l substantially attenuate ,voltages having. lfrequenoies less thansubstantially vfour..cycles pe;- second whereby Said inoideata-1` low ireooeaoy body volt7 ages are substantially attenuated and, said azenhea. sehtative voltages .are passedtherethrough. sohstantially without attenuation..

o. For' use ih an eleetrooardioefaeh rhavilae.- a channel folal amplifyingyvoltages. .transmitted thereto from. the Shbieots boda an esophageal switch adapted. .for` oohheotioh l.to a ,plurality of esophageal' leads nositiohable the .auhieot-e esophagus .for investigating .a condition. `oithe subieota heart. as indioateoioY-voltaeee rence-- sentative of. such CQnQtOlh sadswitoh ,being-5;.

connected tothe input of :saidl chahnelhnd being operable to oohheet. a selected oneef said-leads to. Said ohahnehahdoltee theahs-conhected bea tlteehsaifl 'teh and said. channel .for :soest-.aaa tia y...att.e.hoat,1ha inoioehtal boot Avoltages of. lowe frequency thahsaid sepresentative. voltzntthegotransntissionmf said inci.-. eflllmfli voltare-esto said Channel., .e ih aaeleetroeardiosraphhavinga channel. lier.. :lifying voltages transmitted theeetoitotn. thas for: @smetti-.on to.

L esophagealllead .positionable.4 ih ellloleote e$oi l1aeus for investigating a. oohtlitioho .the sabieets heart. as indoated te? voltages .1 nlresehtatitge, of. such c,ondition,m eans;

adapted-.tor oollhmtlon .toa Source. of body,-volt4 ase-.other than the esonhaeus. omhdioatine volte ma' fepresentative of. such condition atsarid source, ,switch ,Ineens connecteclto.tha l nput, .o:f

Said .ohahhel ionselactivelyy oohnectinesaid .cham J to.. one. .of Salitrneahsand filtermeans. con.-y nected bett' input. .to Said' 'Qhahheh Said' Selector ewitohheins. adapted for .Connection to a Source. ofhody voltage other than the esophagus and being.) operable to 'selectivelyconnect Vsaid 'channel to the output oisaid'- esophageal switch and to sa'idjl other source, saiclv--eso11 hageal switchbeingoperable,` to

connect a selected one of-'sa-id esophageal'leadshaects. body, Ineens adanted,

h;saidifstmehtiohedmeahs .and said..y switch means .for substahtallyl attehuatihg. incidental vhotly,voltages of lower; frequency saidv rst.` mentioned.; nepresentative. voltaugesto..

` of vsaid'esophageal leads to. itsjassociated selector' to f .said selector switch, and ltermeans connectedV between saidv switches folvsuhstantiallyl attenuating incidental: body zvoltages roi' lower frequency than said representative voltages" to prevent the transmission .of said incidental' lower frequency -body voltages through the: selectedV esophageal lead .to-said channel.A

e. For use in a-multiplelead electrocardio-V glaph having a plurality of channels for Aaml-` plifying voltages transmitted thereto from-.the subjects body, a Vsimilar .plurality of 'esophageal' terminals eachadapted for connection` toan esophageal lead. positionable thesubjects` @Sophagus for investigating a,:condition ofwthev subjects heart as indicatedV luy-voltages :repre-- sentative of such. condi-tion,` a similariplurality ot crecer-dial terminals each adapted foriconnection-V tota precordial leadxfrom' the subjects bodyf, a similar. plurality of intra-cardiacy terminals each adapted OrcOnneQt-iQn to. an intra-cardiacfflead. from .the-subjects body, yand a similar.v plural-ity of selectoi` Switches each connected -to the-input of; oneof said channels,-respectively, eachlof .said switches being; operable to'selectively connect an esophageal lead, a precordiallead and an :intracardiac lead to .its associated channel, and filter means connectedhetweeneach offsaid switches and. its; associated esophageal terminal for sub# stantially attenuating incidental-body voltages oflotver frequency than said?treplesentaftiaey volt-y ages to prevent the. transmission of saiddnci-A dentalA lower frequencybody voltages-.throwgh the associated esophageal. lead toi the-r associated channel.;

l0'. Fory use-ln a. multiple.-lead'l electrocardiogt-aph having a plurality of channels. forfamplifylng voltagesl transmitted -tlteletoV from'the subjlects body, a similar plurality oi esophageal switches each adapted foi-*connection toa plu'- ral-,ity oiesophagealleads positionable in the` suba ifeets esophagus `01- investigating alcondition on the .subiects heart asindioatedby -voltaeesrepresentative of such condition,- a similar plurality'. oisnrecordial terminals each-adaptedfor. connes-- r tiony to. a pirecordiallead.mom-.thesubjects body,

of saidselector.svttitchesheng operable toselec.

tively connect one, of said.' esophageal switches, a precordiall lead'and an intra-cardiaclead'iiolit's associated channel, said"4 esophageal lswitches eacnbeing operable to..connect a selected one switch, 'and lte'r meansconnectedbetween each.v esophageal. switch and itsv associated selector` switch .for substantially .a,ttenuatingr incidental body voltages of lower frequency thanisaidl representative voltages. to prevent the .trans-y mission of` said'incide-ntalilwer frequency body. voltages throuehthe selected. esophageal lead toi' the. associated channel..

MIDTON`I-Il PETLAVIN'.v

ReferencesA Cited" in't'he'le. of this 'patent UNITED STATES PATENTS,

Numloen Name.; Daten. 

